I'm new to C# and I'm trying to create a simple program that asks the user to input a filename and some text to then be saved to the newly created file. Maybe I went too fast and did not learn everything I should have about file manipulation. Any help would be appreciated.
Console.WriteLine("Enter name of file then add .txt");
var fileName = Console.ReadLine();
var folderPath = #"C:\Users\Treppy\Desktop\Megatest\";
var filePath = folderPath + fileName;
File.Create(filePath);
Console.WriteLine(filePath);
Console.WriteLine("Enter the text you want to save to that file");
var inputTextUser = Console.ReadLine();
File.AppendAllText(filePath, inputTextUser);
When the application crashes on line 29, I get this message:
System.IO.IOException the process cannot access the file because it is being used by another process.
Line 29 which is the AppendAllText line.
The problem here is that you (your application) still "hold" that file. Actualy, you don't need to create that file, before you write something to it. As stated here AppendAllText will create a file, if it does not exists, so just remove that line, where File.Create(filePath);
You need to close/dispose the previous stream that accessed the file because File.Create keeps the file open and returns a FileStream object.
I checked your code and this solution works.
File.Create(filePath).Close();
OR/AND
File.Create(filePath).Dispose();
Rewrite your code like as
Console.WriteLine("Enter name of file then add .txt");
var fileName = Console.ReadLine();
var folderPath = #"C:\Users\Treppy\Desktop\Megatest\";
var filePath = folderPath + fileName;
Console.WriteLine(filePath);
Console.WriteLine("Enter the text you want to save to that file");
string[] lines = new string[1];
var inputTextUser = Console.ReadLine();
lines[0] = inputTextUser;
//File.AppendAllText(filePath, inputTextUser);
File.WriteAllLines(filePath, lines);
You can write without array
File.WriteAllText(filePath, inputTextUser);
The issue is that the File.Create method keeps the file opened thus the Operating System puts a lock on it. The method returns a FileStream object you can use for read/write access. Before you can write to that file with a different method (such as File.WriteAllText - this method will try to open an already opened file), the FileStream object must be first disposed. See this MS reference.
Simply commenting out that line of code will fix the IOException.
In general, File.Create is not a very commonly used method and is generally used in more specialized cases. If possible, the prefered way is to construct your text file in memory using a string or a StringBuilder then output the contents to file. In your case, that is definitely the approach you want to take. As others have mentioned, you would use File.WriteAllText. It will create the file if it does not exist, or replace the contents of the already existing file. If you want to keep previous content, the use File.AppendAllText as you did in your question. This method will create the file if it does not exist or append the text to the end of the previous content.
Try this:
Console.WriteLine("Enter name of file then add .txt");
var fileName = Console.ReadLine();
var folderPath = #"C:\Users\Treppy\Desktop\Megatest\";
var filePath = System.IO.Path.Combine(folderPath, fileName);
if (!File.Exists(filePath))
{
File.WriteAllText(filePath, "");
}
Console.WriteLine(filePath);
Console.WriteLine("Enter the text you want to save to that file");
var inputTextUser = Console.ReadLine();
File.AppendAllText(filePath, inputTextUser);
That'll stop the File.Create holding the file open with the OS.
Related
Not sure what I am doing wrong. I can create a text file named using Now date and time. My writing to the file fails. If I don't put ".Close()" at the end of the CreateText, it says the file is open by another process when trying to write. With the ".Close()" there are no errors but it doesn't write.
var newFileName = "logs\\" + DateTime.Now.ToString().Replace("/","_").Replace(":","-").Replace(" ","__") + ".txt";
var webRootPath = _environment.WebRootPath;
var dataPath = Path.Combine(webRootPath, newFileName);
System.IO.File.CreateText(dataPath).Close();
System.IO.File.AppendText(dataPath).WriteLine("this is before save");
Just use this:
//System.IO.File.CreateText(dataPath).Close();
System.IO.File.AppendText(dataPath).WriteLine("this is before save");
CreateText() will create a new empty file each time.
AppendText() will create the file if necessary.
But you are leaking file handles here. Appendtext returns a TextWriter that needs to be closed.
Instead of fixing that, consider using a reliable logging packages.
So I'm trying to make a program that calculates and saves your BMI into a file.
I tried using appendtext like this.
StreamWriter logboekBMI = new StreamWriter(path + "Logbmi.txt");
logboekBSA.Close();
logboekBMI = File.AppendText(path + "Logbmi.txt");
logboekBMI.WriteLine("BMI: " + bmi.getBMI());
logboekBMI.Close();
And I read the file to a text box like this:
StreamReader logbmi = new StreamReader(path + "Logbmi.txt");
txtLogboek.Text = logbmi.ReadToEnd();
It deletes the line that was already in the file and inserts the new one. It never appends.
If I understand the question correctly, you want to write text to a file without overwriting any text that is already there.
In that case, you need to define your StreamWriter like so:
StreamWriter logboekBMI = new StreamWriter(path + "Logbmi.txt", true);
The true parameter means that you want to append text to the file. Without it, you are overwriting the file every time you create a new StreamWriter.
Your code seems over complicated for what you want to do. You only need two lines of code, one to save the text and one to read it.
Save text: File.AppendAllText
Opens a file, appends the specified string to the file, and then closes the file. If the file does not exist, this method creates a file, writes the specified string to the file, then closes the file.
File.AppendAllText("C:\path\to\file\Logbmi.txt", "The BMI to add");
Read text: File.ReadAllText
Opens a text file, reads all lines of the file into a string, and then closes the file.
txtLogboek.Text = File.ReadAllText("C:\path\to\file\Logbmi.txt");
I want to create a text file with the extension .jrq and populate it with two lines. However I want this to happen "all at once" instead of creating the text file and then adding the two lines. Basically I need to create an already populated text file.
Here is my current code:
FileStream fileStream = new FileStream(folder + filename + ".jrq", FileMode.Create);
StreamWriter streamWriter = new StreamWriter(fileStream);
streamWriter.WriteLine("Line1");
streamWriter.WriteLine("Line2");
streamWriter.Flush();
streamWriter.Close();
The reason I need the file creation and the file appending to happen together is because I have a windows service that scans the folder that this text file will be created in and that service triggers a job the second it sees a .jrq file (and does logic based on what's written in the file). It notices the .jrq file before I've written anything in it and throws an error.
I think you are better off using a small trick. As adv12 pointed out writing all at once with one single method does not guarantee the implementation is atomic. if I were you I would create a temporary file:
FileStream fileStream = new FileStream(folder + filename + ".tmp",
FileMode.Create);
StreamWriter streamWriter = new StreamWriter(fileStream);
streamWriter.WriteLine("Line1");
streamWriter.WriteLine("Line2");
streamWriter.Flush();
streamWriter.Close();
and then rename it using File.Move:
System.IO.File.Move(folder + filename + ".tmp",folder + filename + ".jrq");
So the job will start when the file jrq is full of data. it's not a super elegant solution but it would work.
Hope it helps.
You could write the file with a different filename, then move it once you've populated it. According to this question, file moves are atomic within NTFS, so your service would never see a half-written file.
File.WriteAllText is what you're looking for. If the file does not exist, it will create it with the text in it on creation.
I have got this read file code from microsoft
#"C:\Users\computing\Documents\mikec\assignment2\task_2.txt"
That works fine when im working on it, but when i am to hand in this assignment my lecturer isn't going to have the same directory as me.
So i was wondering if there is a way to read it from just the file the program is held in?.
I was thinking i could add it as a resource but im not sure if that is the correct way for the assignment it is meant to allow in any file.
Thanks
You can skip the path - this will read file from the working directory of the program.
Just #"task_2.txt" will do.
UPDATE: Please note that method won't work in some circumstances. If your lecturer uses some automated runner (script, application whatsoever) to verify your app then #ken2k's solution will be much more robust.
If you want to read a file from the directory the program is in, then use
using System.IO;
...
string myFileName = "file.txt";
string myFilePath = Path.Combine(Application.StartupPath, myFileName);
EDIT:
More generic solution for non-winforms applications:
string myFilePath = Path.Combine(Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location), myFileName);
If it is a command line application, you should take the file name as a command line argument instead of using a fixed path. Something along the lines of;
public static void Main(string[] args)
{
if (args == null || args.Length != 1)
{
Console.WriteLine("Parameters are not ok, usage: ...");
return;
}
string filename = args[0];
...
...should let you get the filename from the command.
You could use the GetFolderPath method to get the documents folder of the current user:
Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
and to exemplify:
string myDocuments = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
string file = Path.Combine(myDocuments, #"mikec\assignment2\task_2.txt");
// TODO: do something with the file like reading it for example
string contents = File.ReadAllText(file);
Use the relative path.
you can put your file inside the folder where your application resides.
you can use Directory.GetCurrentDirectory().ToString() method to get the current folder of the application in. if you put your files inside a sub folder you can use
Directory.GetCurrentDirectory().ToString() + "\subfolderName\"
File.OpenRead(Directory.GetCurrentDirectory().ToString() + "\fileName.extension")
StreamReader file = new StreamReader(File.OpenRead(Directory.GetCurrentDirectory().ToString() + ""));
string fileTexts = file.ReadToEnd();
I am getting the "The process cannot the file X because it is being used by another process" when I execute the following piece of code in my console application:
List<string> lines1 = new List<string>();
List<string> lines2 = new List<string>();
string path1 = ConfigurationManager.AppSettings.Get("path1");
string path2 = ConfigurationManager.AppSettings.Get("path2");
File.Create(path1);
File.Create(path2);
foreach (object myObject in myObjects)
{
//do some fancy logic here!!!
}
File.WriteAllLines(path1, lines1.ToArray()); //exception is thrown here
File.WriteAllLines(path2, lines2.ToArray());
How can I resolve this issue?
The likely problem here is the File.Create method. It's creating and returning a handle to the file in question wrapped in a FileStream object. That object is holding the file open for write and is hence blocking your later File.WriteAllLines call.
The simplest solution is to remove the File.Create calls. Just let the WriteAllLines method create the file for you
You have two options: File.Create not only creates the file but OPENS it. so you need to keep a reference to the filestream and close it like this:
var file1 = File.Create(path1);
var file2 = File.Create(path2);
file1.Close();
file2.Close();
OR you can just skip that because File.WriteAllLines(...) will create a file if it doesn't already exist.
You probably want to leverage something like File.Exist to prevent other exceptions, but that is not part of the present question.
File.Create(path1) is opening and keeping the file open and hence locking it.
File.WriteAllLines will create the file , so there is no need to create it first.
If you need to create it first (eg to test the path) you can do
FileStream fs = File.Create(path1);
fs.Close();
As per my comment above, File.Create(..) returns a FileStream object, which won't be destroyed until the method is closed (which means the handle is still open, thus file is still locked). When you're trying to use WriteAllLines it's attempting to open a new handle, and failing because one's already open.
You can use code like the following, which works fine (just tested):
List<string> lines1 = new List<string>();
string path1 = #"C:\Development\test1.txt";
for (int i = 0; i < 20; i++)
lines1.Add("Test " + i);
TextWriter textWriter = new StreamWriter(File.Create(path1));
foreach(string line in lines1)
textWriter.WriteLine(line);
textWriter.Close();
The code above will utilise the same stream that was created when the file was created, so you have no chance of collision.
Alternatively as in other answers, the File.WriteAllLines method will create the file for you anyway!
If you delete the File.Create lines, you should be fine. Unless you're doing something with the files in your foreach loop, you don't need to call the File.Create methods at all. The File.WriteAllLines will create a file if it doesn't exist. Since the File.WriteAllLines method also closes the filestream, you don't have to worry about managing the filestream returned by a File.Create.